Patterns of Thyroid Function in Metabolic Syndrome Patients and Its Relationship with Components of Metabolic Syndrome

Abstract

Background: Metabolic syndrome (MetS) is a cluster of metabolic abnormalities characterized by central obesity, hyperglycemia plus insulin resistance, hypertriglyceridaemia plus low high density lipoprotein (HDL) cholesterol and hypertension. This cluster of metabolic syndrome is associated with some of the endocrine disorders prominently thyroid dysfunction. Thyroid dysfunction and metabolic syndrome are both associated with cardiovascular disease risk conversely increasing both morbidity and mortality. Objectives: This study was carried out to evaluate thyroid function in patients with metabolic syndrome and to assess its relationship with the components of metabolic syndrome in a tertiary care hospital. Methods: A cross sectional study was carried out among metabolic syndrome patients attending Hormone and Diabetes clinic in a tertiary care hospital, Dhaka, Bangladesh during June 2019 to March 2020. We included 346 patients who fulfilled National Cholesterol Education Program-Adult Treatment Panel (NCEP ATP) III criteria. Anthropometric parameters include; height, weight and waist circumference were measured and blood pressure were taken in standard conditions. Fasting blood samples were analyzed to measure glucose, triglyceride (TG), high density lipoprotein (HDL) cholesterol and thyroid hormones [Thyroid stimulating hormone (TSH) and Free Thyroxine (FT4)]. Patients categorized as euthyroid if all thyroid hormone levels fell within normal reference range [TSH: 0.47-5.0mIU/L; FT4: 0.71-1.85 ng/dL]. Subclinical hypothyroidism (SCH) was considered if TSH >5.0mIU/L and free T4 is within normal reference value (0.71-1.85 ng/dL). Conversely, overt hypothyroidism was diagnosed if TSH >5.0 mIU/L and freeT4<0.71 ng/dL. Results: Among study population 22.8% were males and 77.2% were females, with mean age of 42.61±9.13 years. Average body mass index (BMI) of the study subjects was 26.37±3.78 kg/m². Thyroid dysfunction was seen in 47.1% of metabolic syndrome patients. The prime thyroid dysfunction was subclinical hypothyroidism (34.4%) followed by overt hypothyroidism (12.7%). Thyroid dysfunction was much common in females (37.3%) than males (9.9%) but was not statistically significant; [p=0.19]. Triglyceride showed significant positive correlation with TSH level (r=0.168, p<0.05) but negative correlation with free T4 (r=-0.200, p=<0.001). However, HDL cholesterol showed significant negative correlation with TSH level (r=-0.150, p<0.05). Conclusions: Our study recognizes thyroid dysfunction in metabolic syndrome patients; subclinical hypothyroidism was the commonest followed by overt hypothyroidism. The current study also correlates thyroid function with some components of metabolic syndrome (high density lipoprotein cholesterol and triglycerides).